This is a basic tool to query modbus elements.
Modbus is a protocol designed for communicating between electronic devices designed in the 1970s that continues to be used today despite modern alternatives existing.
Modbus can be found in a wide variety of devices, my particular use case is around solar power systems which often have an undocumented modbus interface designed to be used with the manufacturer's add-on devices, which are universally awful.
This tool allows you to query individual addresses or an address block at a time, and output the results in a few formats. You could use this within a script to collect many data points, or use it to probe a modbus device to discover its usable endpoints.
You can now write a value to a single address as well.
If you have a Go compiler installed, simply
go get github.com/squash/modbus-cli
This will download, complile, and install to your GOROOT/bin directory.
Run modbus-cli with -h for a list of options.